1. Field of the Invention
The present invention is related to a pulling device in a joint of a foldable ladder, particularly to a pulling device of simplified structure and improved operation.
2. Description of Related Art
A joint for a foldable ladder has been disclosed in the German Utility Model No. 29600583,5. Therein, as shown in FIG. 5, three gliding pins 8 are each connected with a spring 9 to form three pulling devices. A handle 7 allows to vary the opening angle of the foldable ladder between three different adjustments. This arrangement has few structural parts and thus works reliably.
The main characteristic of the present invention is that a single spring is substituted for the three springs 9. An arc-shaped part connects the three gliding pins 8, forming a single pulling device. The handle 7 for unlocking the joint, when operated, is exposed to an elastic force from the pulling device. Since the three gliding pins 8 are connected by the arc-shaped part, they will be moved along a circular line. Thus reliable functioning of the pulling device is ensured. At the same time, the number of structural parts is reduced.
The present invention can be more fully understood by reference to the following description and accompanying drawings.